3.9G is at the moment standardized in 3GPP as System Architecture Evolution (SAE). One of the targets has been to simplify the use of contexts and Access Point Names, APNs, in the 3.9G system. An APN provides routing information e.g. for SGSNs, Serving GPRS Support Nodes, and GGSNs, Gateway GPRS Support Nodes providing access points to networks.
At the moment, the assumption is that a default IP context is created when the UE registers to the 3.9G network. In 2G/3G terms, this means merging attach and PDP context activation procedures. In 2G/3G, the UE specified APN when activating a PDP context, but in 3.9G, there may be no need for the UE to request APN at registration, but the network can determine the default APN. The UE and the network should, however, have the same understanding on the default APN. This may be achieved e.g. by configuring the default APN to the UE or by indicating the default APN from the network to the UE when selected (i.e. at registration). An IP address is allocated for the default IP context. Secondary IP contexts with the same IP address may be created on need basis.
There may be use cases, when the subscriber wants to use both visited and home services at the same time. One such use case is a roaming subscriber who wants to have Internet access through the visited network and in parallel use a service such as Multimedia Messaging, MMS, through the home network. If the 2G/3G solution is re-used in 3.9G, this requires two IP contexts with two APNs.
FIG. 1 shows a structure wherein two contexts are required with two APNs. A user terminal 1 such as a mobile user equipment has stored or assigned a Visited IP Address and a Home IP Address for the two APNs. The terminal 1 can communicate with a visited eGGSN 2 (“e” stands for “enhanced” or “evolved”) using the APN of the visited eGGSN 2 for getting access to visited services 3 which may be provided through a network visited by the terminal 1. The terminal 1 can further communicate with another visited eGGSN 4 using the other APN for getting access to home services 3 which may be provided through a network visited by the terminal 1. The visited eGGSN 4 communicates with a home eGGSN 5 providing access to home services 6 which may be provided in a home network of the terminal 1. The nodes 2, 4 stores and use two IP contexts for the two IP addresses of the terminal 1.